This invention relates, generally, to liquid natural gas (LNG) delivery systems and, more particularly, to a no loss fueling station particularly suited for use with natural gas powered motor vehicles.
In recent years great efforts have been made to find and develop a cheaper and more reliable domestic energy alternative to foreign fuel oil. One such alternative is natural gas which is domestically available, plentiful, relatively inexpensive and environmentally safe as compared to oil. Because one of the largest uses for fuel oil is as a fuel for motor vehicles, great strides have been made to develop fuel systems for motor vehicles that utilize natural gas.
One possibility is a dual-fuel modified diesel engine that runs on a 60/40 diesel fuel to LNG mixture. While this engine substantially reduces diesel fuel consumption, it requires that the LNG be delivered to the engine at approximately 300 psi, a pressure approximately six times the normal storage pressure for LNG. Other natural gas powered engines require that the LNG be delivered at pressures ranging from less than 50 psi to more than 500 psi. Also, the vehicles being filled can be at a variety of conditions from being full at high pressure to being completely empty at low pressure or any combination thereof. Therefore, an LNG fueling station that can deliver LNG to vehicles having wide variations in fuel tank conditions is desired.
A further complicating factor is that LNG is an extremely volatile substance that is greatly affected by changes in temperature and pressure. As a result, the fueling station must be able to accommodate fluctuations in pressure and temperature and transitions between the liquid and gas states resulting from heat inclusion that inevitably occurs in cryogenic systems. Optimally, the fueling station should be able to meet these conditions without venting LNG to the atmosphere because venting LNG is wasteful and potentially dangerous. One such fueling station is disclosed in U.S. Pat. No. 5,121,609.
Thus, a no loss fueling station that is efficient, safe and can deliver LNG at a range of temperatures, pressures and operating conditions is desired.